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use integer_encoding::VarIntAsyncWriter;
use libipld::Cid;
use tokio::io::{AsyncWrite, AsyncWriteExt};
use super::{error::Error, header::CarHeader};
#[derive(Debug)]
pub struct CarWriter<W> {
header: CarHeader,
writer: W,
cid_buffer: Vec<u8>,
is_header_written: bool,
}
impl<W> CarWriter<W>
where
W: AsyncWrite + Send + Unpin,
{
pub fn new(header: CarHeader, writer: W) -> Self {
CarWriter {
header,
writer,
cid_buffer: Vec::new(),
is_header_written: false,
}
}
/// Writes header and stream of data to writer in Car format.
pub async fn write<T>(&mut self, cid: Cid, data: T) -> Result<(), Error>
where
T: AsRef<[u8]>,
{
if !self.is_header_written {
// Write header bytes
let header_bytes = self.header.encode()?;
self.writer.write_varint_async(header_bytes.len()).await?;
self.writer.write_all(&header_bytes).await?;
self.is_header_written = true;
}
// Write the given block.
self.cid_buffer.clear();
cid.write_bytes(&mut self.cid_buffer).expect("vec write");
let data = data.as_ref();
let len = self.cid_buffer.len() + data.len();
self.writer.write_varint_async(len).await?;
self.writer.write_all(&self.cid_buffer).await?;
self.writer.write_all(data).await?;
Ok(())
}
/// Finishes writing, including flushing and returns the writer.
pub async fn finish(mut self) -> Result<W, Error> {
self.flush().await?;
Ok(self.writer)
}
/// Flushes the underlying writer.
pub async fn flush(&mut self) -> Result<(), Error> {
self.writer.flush().await?;
Ok(())
}
/// Consumes the [`CarWriter`] and returns the underlying writer.
pub fn into_inner(self) -> W {
self.writer
}
}
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